1. Field of the Invention
The present invention relates to an oxidizing composition (or oxidant composition) in the form of powder, which is applicable to a chemiluminescence reaction (or chemical reaction for emitting chemiluminescence) of a chemiluminescent substance (or chemiluminescence-emitting substrate), and to a method of measuring chemiluminescence by using the oxidizing composition. The oxidizing composition and the measurement method according to the present invention are particularly suitable for qualitative or quantitative analysis of a biological substance and/or another minor (or trace) substance.
2. Related Background Art
Chemiluminescence is luminescence as a result of a chemical reaction. A chemiluminescence course or process generally includes a step in which molecules are excited in a chemical reaction to be converted into an excited state via a transition state, and the molecules are then caused to emit light while they are returned to the ground state.
The fluorometry (i.e., analytical method utilizing fluorescence), which is one of typical high-sensitivity analytical methods for measuring substances, requires a light source (or excitation source) such as xenon lamp for exciting fluorescent molecules. Accordingly, in a case where the fluorometry is applied to high-sensitivity analysis, the background level in the measurement is liable to be elevated because of a stray light phenomenon due to the light source and of Raman effect (or Raman light) due to a solvent to be used in the measurement. Further, the background level in this analysis is liable to vary due to fluctuation in the light emitted from the light source. Consequently, when the sensitivity of a detector to be used for the fluorometry is simply enhanced in the fluorometry, the noise level in the measurement is also elevated along with an increase in the signal level.
On the other hand, high-sensitivity analysis on the basis of chemiluminescence (hereinafter called `chemiluminescence analysis`) has been focused in recent years. In the chemiluminescence analysis, since chemiluminescent molecules are excited on the basis of a chemical reaction (or chemical energy), additional light source as an excitation source is not required. Thus, the chemiluminescence analysis has an advantage such that the sensitivity of a detector to be used therefor may be increased without consideration of the above-mentioned effect of a light source on the measurement. In addition, the chemiluminescence analysis also has other advantages such that it has a wide dynamic range, it can use a relatively simple detector, and it takes a relatively short period of time for the measurement (e.g., as described in "Kagaku Kogyo Shiryo", Vol. 22 (No. 4), pp. 111-127 (1987) written by Honda, K), which is hereby incorporated by references.
When an organic compound is used as chemiluminescent molecules, chemiluminescence emission is effected through an oxidation reaction in many cases. In such a case, hydrogen peroxide (H.sub.2 O.sub.2) is typically used as an oxidizing agent for accelerating the oxidation reaction. For example, when an organic chemiluminescent composition such as luminol derivative or an acridine derivative is used as a chemiluminescent molecules, a basic (or alkaline) hydrogen peroxide is added to such chemiluminescent molecules in order to convert the molecules into an excited state and cause them to emit chemiluminescence (e.g., as described in Imai, K. "SEIBUTSU HAKKO-TO-KAGAKU HAKKO (Bioluminescence and Chemiluminescence)", p.83, published by Hirokawa Publishing Co. Tokyo JAPAN), the disclosure of which is hereby incorporated by references. In addition, an acridinium ester capable of emitting chemiluminescence is used as a high-specific-activity label in immunoassay in Weeks, I., et al.; Clinical Chemistry, Vol.29 (8), pp.1474-1479, (1983), which is hereby incorporated by references.
In recent years, detection method of a trace substance with a higher sensitivity has been expected, and various luminescent molecules or substances having a higher quantum efficiency have been developed (e.g., as described in the "SEIBUTSU HAKKO-TO-KAGAKU HAKKO(Bioluminescence and Chemiluminescence)", p. 79 and p. 103).
However, the operability such as portability or workability in the above-mentioned conventional chemiluminescent systems is poor.